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Hi everyone. I am a new member here as well as a new Infinity system owner of a few months.

The system consists of a 38TDB, 58MVP, Infinity D01 controller and a fan powered humidifier. The Infinity system runs great, with no issues to date. But I am very interested in finding out what makes this system tick, or what functions and algorithms are used by the Infinity controller.

There seems to be very little documentation provided by Carrier (or at least what I can find!) on the controller algorithms. There have been some discussions on this site that I have searched out, and many of you seem to be familiar with the system. If I recall correctly, one member was part of the engineering team that worked on the programming.

They cut off the engineer's fingers so that he couldn't post here any more.

It's a Proportional-Integral (PI) algorithm. P - setpoint error. I - time of error. Algorithm value builds and controller energizes stages based upon values that we don't get to see. As algorithm unwinds, stages of heating or cooling are removed. If P or I hit a certain value, a stage will be energized regardless of algorithm value.

It's not really magic. Just doesn't use standard setpoint error control that we are used to seeing in older or less expensive thermostats.

Cool-to-dehumidify is controlled in different manner: Must be above dehumidify setpoint; room temp must be less than three degrees below the setpoint for temperature, and room temp must be above 70 degrees. Also, as the room temperature goes below 75 degrees, dehumidify setpoint raises 2% for every degree below 75.

I'm certain that there's a little more to the dehumidify function, but that's all we've beat from Carrier so far.

nascar, I believe dash is right, it was chrisp who indicated he was from the Carrier engineering group.

jrbenny, thanks for the input. What you say is pretty well what I have been able to piece together from this site and Carrier documentation. The dehumidify function seems to be the biggest mystery.

Carrier has done a great job with this system, making it functional and idiot proof (that's me) at the same time, but it would be much easier to set up with more documentation.

The dehumidify function seems to not work as well when the fan is set to manual, even at the low setting. Do you think that is due to the air movement in the house, or is the system designed to not call up the dehumidify function if the fan is not set to auto?

I also am wondering why Carrier programmed more than one humidity setting. The heat setting goes from 5% to 45% the cool goes from 46% to 58%. I'm not completely sure, but it looks like the heat function does not respond to high humidity, over 45%, and is only concerned if the humidity is below it's setpoint? If it's a cold wet day I would like the furnace to respond to high humidity, not wait for the AC to kick in which it might not do if the temp is below the cooling lockout setting.